Stuck in Convict Conditioning

Dear Primal Friends,

I am currently experiencing difficulty with Convict Conditioning. I seem to have trouble performing uneven squats and hanging bent leg raises. When I perform uneven squats, all my weight seems to transform over to the supporting toes. On hanging bent leg raises, I get sharp lower back pain. I don't experience any lower back pain when performing hanging knee raises. Does anyone have suggestions on how to overcome these obstacles?

Skip the uneven squats. The ball seems to add a level of difficulty that is not terribly helpful. I feel like I could go back to them to build up flexibility/tension in my raised leg, but I don't think they did anything useful for getting me to a pistol squat. What worked for me was half-pistol squats to a chair, then a low bench, then a lower stool, then all the way down.

The whole premise of CC (and Naked Warrior, and Fitness 666) is to find small steps to work up to harder exercises. Can you bring your knees up, then extend to bent leg and lower slowly? Have you been working on bridging? Do straight-leg raises while lying on the floor cause the same problem? Bent-leg?

It could be a lack of strength, and it could be a mobility issue/old injury/etc of some sort. Hard to say from here.